1. Field of the Invention
The present invention relates to telecommunication technology and, in particular, to a method and system for encryption and decryption of short messages and for authentication of the sender in a telecommunication system.
2. Description of Related Art
Telecommunication networks, as for example GSM (Global System for Mobile communications) networks, utilize heavy encryption of speech transmission in the radio link between a mobile station and the base station serving the mobile station. In addition to voice communication, the use of text messages for effecting communication via mobile stations has significantly increased. Moreover, with the rise of service standards, services based on text communication have become common. Such text communication can be utilized for and in connection with a wide variety of service functions, as in effecting payment for services. One current obstacle to easy encryption of messages is the fact that mobile stations consistent with and utilizing current mobile communication standards do not permit changes that would facilitate encryption. Indeed, at present the only component of conventional mobile stations that is sufficiently standardized and allows encryption is the subscriber identity module (SIM).
Mobile telephones consistent with current mobile communication standards, such as the GSM standard, do not directly provide the ability or possibility of using encryption in text communication by and between mobile stations. Thus, although text communication can be used to implement services requiring a high level of data security, services requiring such high levels of data security cannot become common before sufficient encryption of messages is available.
Currently known are closed user group solutions in mobile communication networks that are, for example, implemented on the basis of the mobile telephone numbers of the mobile devices or stations. In these applications, a message is delivered separately to each person included in a distribution list without respect to each recipient's location. A considerable drawback to this system is that the message delivery time varies considerably between the first and last persons on the distribution list.
One serious existing problem with message communication under current mobile communication standards is that it is possible for a third party to read the contents of a text message. A further problem is the lack of a practical way to encrypt the messages relating to different services so that the receiver can ascertain the identity of the sender. Still another difficulty is encountered in the sending of encrypted messages to a closed receiver group in a given or predetermined geographic area.